High temperature oven structure



March 10, 1970 l w. T. KEMP- 3,499,430

l HIGH TEMPERATURE OVEN STRUCTURE Filed April 5, 1968 2 Sheets-Sheet 1 WAY E 7T KEMP March 10, 1970 w. 1". KEMP l HIGH' TEMPERATURE OVEN STRUCTURE 2 Sheets-Sheet 2 Filed April s, 1968 E un/nnnnunnu C Ff@ 2 NVENTOR WA E 7.' KEMP United States Patent Oli ice 3,499,430y Patented Mar. 10, 1970 3,499,430 HIGH TEMPERATURE OVEN STRUCTURE Wayne T. Kemp, Kutztown, Pa., assignor to Calorie 'Corporation, Topton, Pa., a corporation of Pennsylvania Filed Apr. 3, 1968, Ser. No. 718,590

Int. Cl. F24c 15/32 U.S. Cl. 126-21 8 Claims ABSTRACT F THE DISCLOSURE A household range having an oven adapted to be operated at high temperatures and having heat protecting means therefor comprising a dilution flue disposed outwardly of one of the oven walls, which flue contains a ue box overlying an exhaust opening in the wall, the ue passing cool air from an area beneath the level of the opening upwardly and outwardly ofthe range through upper vents, the flue box being positioned to receive degradation products exhausted by the oven through the exhaust opening, the flow of exhausted products mixing with the cool'air ow in an upper portion of the flue. Additional means for cooling the outer wall of the range comprises a second cool air flue spaced outwardly of the rst flue, and batldes in said ilues for preventing heat in the area of the exhaust opening from overheating the outer wall of the range.

BACKGROUND OF THE INVENTION This invention relates generally to household ranges and has particular reference to ovens, particularly ovens operated at high temperatures such as occur during pyrolytic-type self-cleaning operations. The present invention can be utilized in any range or oven wherein degradation products within the oven are exhausted through an opening in one of the walls of the oven.

The invention is described and illustrated in connection with an oven having gas-fueled Ibroil and bake heating elements which can be operated independently for broil or bake operations or can be operated simultaneously for self-cleaning operations, but it is to be understood that the heating elements may be electrical or may be fueled by other than gas, if desired. A more complete description of a gas-fueled oven of the character described can be found in copending application Ser. No. 718,129 assigned to the same assignee as the present application. One type of electrical oven which could be modied t0 incorporate the present invention is shown and described in U.S. Patent No. 3,121,158.

In a self-cleaning oven there are provided upper and lower heating elements which are simultaneously operable to raise the temperature of the oven interior to a high enough level which will cause pyrolytic action to occur in food soils accumulated on the walls of the oven cavity. Such pyrolytic action, which occurs at various temperatures above 750 F., depending upon the constituents of the food soils, causes conversion of the soils into corresponding gaseous degradation products, which degradation products are exhausted to the exterior of the oven as they are produced so as to prevent any subsequent substantial condensation thereof upon the interior surfaces of the oven cavity. Such degradation products include, among other things, smoke, carbon monoxide, and other constituents which must be elminated before the degradation products are allowed to be exhausted into a kitchen atmosphere. This vhas been achieved in electrical self-cleaning ovens by the incorporation in the exhaust passage of a catalytic unit which promotes the oxidation of carbon and carbon compounds and thus eliminates the objectionable constituents which come in Contact with it during the exhaust process. In a gas-fueled oven such as set forth in the aforesaid copending application Ser. No. 718,l29, the upper heating element or burner is of a broad flame radiant energy type which covers a substantial area of the oven adjacent its upper extremity and is located in such a position as to intercept the ow of degradation products before they pass outwardly through the exhaust vent. The broad ame consumes the smoke and other degradation products by incineration whereby the products which eventually are exhausted from the oven are substantially clear, odorless and invisible.

Self-cleaning ovens are adapted to be operated at relatively high temperatures. For example, pyrolytic action occurs in food soils at temperatures above about 750 F., depending upon the particular constituents of the food soils. It has been found that, with higher temperature levels, self-cleaning time cycles may be shortened, and at a mean temperature of about 985 F., for a time period of about 70-80 minutes duration, an oven will normally become completely cleaned. It will be apparent that during the self-cleaning operation the exhausted degradation products are themselves at relatively high temperatures. Therefore, a serious problem exists in that, as the products are exhausted through the exhaust vent into a suitable flue which may be located, for example, at the rear of the oven outwardly of the oven rear wall, the outer wall of the range will become extremely hot. Such overheating of the outer wall or panel of the range can create a re hazard, particularly when the range wall is positioned in relatively close proximity to a wall of the kitchen.

SUMMARY OF THE INVENTION The present invention relates to a cooling structure for self-cleaning ovens which solves the foregoing problems concerned with ovens operated at high temperatures and particularly ovens which are adapted to exhaust high-temperature products whereby heat is transmitted to external surfaces. In the present invention there is employed a dilution flue which is located between the outer wall or panel of the range or oven and the wall of the oven liner which contains the exhaust vent. The dilution ue receives from the lower regions of the range or oven a supply of cool air which passes upwardly through the flue and exits through openings provided therefor in the upper regions of the structure. Within the dilution flue is located a ue box which is positioned opposite the exhaust vent and spa-ced from the rear wall of the flue. The air containing degradation products which is being exhausted from the oven through the exhaust vent passes into the Hue box and flows upwardly out of the ue box. The cool air moving upwardly through the llue box passes over the surface of the flue box Walls and tends to assist in reducing the temperature of the box. Above the flue box the flowing cool air merges with the oven exhaust products and exits through the vents provided therefor in the backsplash of the range. The flue box is preferably provided with a curved or V- shaped internal baille which tends to deflect the upwardly owing products passing therethrough above the exhaust vent so that this air, which contains the heated exhaust from the oven, will be distributed over a wider area of the back panel ofthe oven and, consequently, over a wider area of the ue whereupon it will be more eiliciently cooled.

In a further embodiment of this invention, there is provided a separate vertically extending flue outwardly of the first-mentioned flue, which second ue may communicate with an area immediately above the floor of the kitchen below a transversely extending panel which is provided for aiding in preventing the floor from becoming overheated by heat directed downwardly from the oven. The cool air from this area immediately above the floor passes through the second flue upwardly over the rear surface of the first flue and thence outwardly through another series of vents provided therefor in the backsplash of the range.

Each of the fiues may be provided with additional baffles or reflecting plates, if desired, to prevent excess heat from being transmitted to the outermost wall or panel of the range. If desired, the first and second fiues may be separated by an intermediately disposed panel or wall which extends only for a relatively short distance below the level of the exhaust duct in cases where the floor-protecting panel is not required.

The presently described invention enables a range or oven to be provided with outer walls or panels which are maintained at a sufficiently cool temperature as to enable the appliance to be installed flush with a wall without hazard from excessively high temperatures.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objectives of this invention will become apparent from the following description taken in connection with the drawings, wherein:

FIG. 1 is a side elevational view partly in section of a range embodying a preferred form of the invention;

FIG. 2 is a reduced front elevational view of the range shown in FIG. l;

FIG. 3 is an enlarged vertical sectional view partly in elevation illustrating a modification in the flue and bafile structures; and

FIG. 4 is a front elevational view partly in section of the flue box and rst fiue structure.

DESCRIPTION OF 'FI-IE PREFERRED EMBODIMENTS Referring more particularly to the drawings wherein like characters of reference designate like parts throughout the several views, the kitchen range depicted in FIG. 1 and FIG. 2, which is primarily gas fueled in nature, is shown without the top burners and gas supply connections thereto which do not in themselves constitute any part of this invention. Likewise, details of the controls for the top burners have also been omitted from the drawings, as well as details of the controls for the oven burners since such controls in themselves also constitute no part of the present invention.

More particularly, the range comprises an upstanding, substantially box-like metal body 12 carrying a substantially horizontal metal cooking top 14 and upstanding metal backsplash 16 and sidesplashes 18 arranged respectively at the back and sides of the cooking top 14.

Within the body 12 is a substantially box-shaped metal liner 20 which defines an oven cooking cavity 22 and comprises a rear wall 24, a top wall 26, a bottom wall 28, and a pair of side walls. The interior surfaces of the liner 20 may be finished in any conventional manner such as, for example, by carrying a layer of porcelain enamel of the glass-frit type, not shown. A front opening is provided in the front wall of the range, and an aligned front opening is provided in the liner front wall 30, whereby the interior of the oven cooking cavity 22 is accessible from the front of the `body through the two front openings mentioned. A front door 32 is mounted upon the front of the body 10 by a suitable hinge structure (not shown) whereby the door is pivotally movable into open or closed relation with respect to the open front of the cavity 22. The door, hinge, and latching structure are not shown and do not constitute in themselves part of the present invention.

The liner top wall 26 is spaced well below the cooking top 14 and heat-insulated therefrom by a bolt 34 of fibrous glass or other selected insulating material which is intended to aid in confining heat as much as possible to the interior of the cavity 22 during operation of the oven. The door 32 may be similarly filled with insulating material 36, and at the back of the range a rear insulation wall or shield 38 is provided in spaced relation with the oven rear wall 24, and the space therebetween is also filled with insulation 40. Thus, the top, sides, rear and front of the oven are insulated from the adjacent por tions of the range and from the exterior atmosphere. At the bottom of the range is a heat-reflecting shield or plate 42, provided for reflecting heat toward the oven 20 and thus serving to protect the floor beneath the range.

In accordance with this invention, there is provided a lower burner 44 which is located in the cavity 46 beneath the liner bottom wall 28 and above shield 42. Burner 44 extends a substantial distance across the width of the cavity 46 and is of a conventional blue-flame type which includes a ported burner head 48 having a gas-receiving chamber for receiving gaseous fuel from a venturi or the like 50, which is suitably mounted to receive gas from a supply line 52 and to admixture the gas with air in the conventional and well-known manner. A constantly burning pilot light 54 is suitably connected into the gas supply system and is located adjacent the burner head 44 so that jets of flame will be ignited at each of the ports in the head when the control system (not shown) is operated to allow gas to flow into the head.

The lower burner head 44 is enclosed within the cavity 46 on the bottom and sides by a heat-reflecting shield 56 the bottom of which is mounted above and spaced from shield 42 and which has side portions or win gs 58 angled upwardly and outwardly to deliect heat toward the bottom wall 28 of the oven liner 20. Suitable vents 60 and 61 are, of course, provided in the shields 56 and 42 to insure that suicient air enters the cavity 46 to sustain combustion. The deliectors 58 are provided with suitable direct connections to the oven side and back walls, as is the bottom wall 28, so that heat therein will be transmitted by convection to the oven wall surfaces. Beneath and spaced from shield 42 there is located another transversely extending heat protecting composite shield or panel 63 which preferably comprises a multi-layer structure embodying a sheet of asbestos sandwiched between sheets of metal.

The burner head 48 is provided with longitudinally spaced ports so that upon operation of the control system (not shown), which may be located in the control panel 62, a number of jets of blue flame will project outwardly from the respective ports in the normal manner of a burner of this type. The control system, which is not shown, may include suitable selector switches which may be manually set to indicate off, bake, time-bake, broil and clean, for example, and may be suitably connected to valve systems for controlling the flow of gas to the lower ported burner 44 and to the upper radiant burner to be described hereinafter. The switches may also be provided with temperatureindicating indicia whereby the maximum temperature at which the oven is to be maintained during a baking operation by the burner 44, for example, may be set, which temperature may be, for example, 150, etc., which has reference to F. The broil selection may be approximately 600 F., and the clean selection may be approximately 985 F., for example, as more fully explained hereinafter. The control system, of course, will include the required temperature sensors, thermostats, switches, timers, circuitry and other components as may be required to control the iiow of gas into the burners in accordance with the required time and temperature to be maintained in the oven.

In the oven cavity at the upper extremity thereof is a radiant burner 64 of a type which produces a broad sheet of flame or incandescence. One example of a radiant burner of a type suitable for use in the self-clean oven of the present invention is that disclosed in U.S. Patent No. 3,122,197. This burner comprises a device wherein gas is burned on the surface of a screen to heat the screen to incandescence. Such a radiant burner 64 includes a burner head 66 defining an open-sided cavity, and a mixing chamber such as a venturi 68 which has its inner end communicating with the burner cavity and the outer end 70 adapted to receive gas from pipe 72. The mixing chamber 68, for eicient and rapid combustion, is required to receive an ample supply of primary combustion air. For example, ten parts of air to one part of gas is considered to be one satisfactory ratio in the case of natural gas. To insure an adequate supply of uncontaminated primary combustion air, the mixing chamber 68 is made in the nature of an oversized venturi and its outer end 70 is bell-shaped, as shown in FIGS. 1 and 3. End 70 is considerably larger than and enicrcles the outlet 74 of pipe 72 so that the amount of combustion air entrained by the gas will be adequate.

The pipe 72 is connected to the supply line 52 and is also connected into the control system (not shown) so that, when the control system is operated to allow gas to ilow from pipe 72 into mixing chamber 68, where it becomes mixed with air, and then into burner head 66, it will become ignited by a constantly burning flame of a pilot light 78. This creates a broad flame which radiates infra-red energy throughout the oven cavity.

It will be understood, as pointed out before, that the burners 44 and 64 may be operated individually and separately from one another for conventional baking and broiling operations. However, both burners are operated simultaneously for performing a self-cleaning operation, although one burner may be operated for a short time before the other at the start of a self-cleaning operation, and one or both burners may be intermittently operated or modulated during a self-cleaning cycle in order to maintain a required temperature level.

The presently described self-cleaning oven operates to quickly raise the temperature in the interior of the oven to approximately 1040 F., for example, although this may vary slightly, and then the mean temperature levels off at about 985 F., for example. It has been found that self-cleaning occurs at a temperature which, for most cooking materials, is above about 750 F. It is known that with higher temperatures, shorter time periods are required for food soils to be removed by pyrolytic action. The upper temperature levels may be established in accordance with the particular design of the oven; that is, higher temperatures and shorter time cycles may be used if heavier insulation and fire protection are provided. However, it has been found that a leveling-off temperature of about 985 F. can be maintained with a gas oven which is properly insulated without requiring complete redesign of the oven or the use of economically unreasonable amounts or types of insulation, and that the temperatures of the outer walls of the range and of the surrounding walls and oor will not become undesirably heated. It is to be understood, therefore, that the temperatures and time cycles set forth herein are exemplary only and may vary from range to range or with different oven and range constructions.

The presently described gas-fueled oven can be raised to a temperature of about from 10001040 F. within about 25-35 minutes, for example. It reaches the selfcleaning temperature of 750 F. in about ten minutes, then continues up to the 1040 F. level in about an additional ten-fifteen minutes, finally leveling off at about 985 F. for about 5 5-65 minutes, at which time the oven has become completely cleaned. Then the control system shuts off the flow of fuel to the burners, and the oven is allowed to cool. In about -20 minutes the oven temperature is low enough to permit the oven door to be opened. Thus, the presently described oven operates above about 750 F. to self-clean for about 70-80 minutes and performs almost its entire cleaning during a period of about 55-65 minutes when it is actually above a level of 950 F., although admittedly a slight amount of cleaning starts to occur when the oven is being initially raised from the 750 F. level to the 950 F. level, which process may take from about 10-15 minutes.

It has been discovered that the range of compounds of which food soils are composed may be decomposed or degraded by heat during the time interval of about 70- minutes when the temperature is above about 750 F., which process will produce substantial amounts of gaseous degradation products.

In the heat-cleaning cycle, a sweep of ambient air proceeds upwardly through the oven cavity from beneath the heat shields 42 and 56, through openings 84 (FIG. l) in the side, front, or back edges of the oven bottom 28, and out through an exit or exhaust opening 86 (FIGS. 1 and 3) into a flue or duct 88 from which it flows out of the range through a series of openings 90 in the front of the backsplash 16. This flow of air carries the gaseous degradation products resulting from the pyrolysis of -food soils during a self-cleaning cycle.

The lower end of the flue 88 communicates directly with the fresh air supply beneath the lower shield 63. It will be apparent that a flow of fresh air will be constantly maintained because of the tendency of heated air to rise. However, if desired, a fan may be inserted beneath the range or on the lower portion of ue 88 to additionally urge the flow of air through the ue. Thus, cool air is made to ow through the flue 88, and the gaseous degradation products are satisfactorily removed from the interior of the oven without the necessity for additional appurtenances such as catalytic oxidizing units, etc.

In FIG. 1, lines A indicate the flow of combustion products, or degradation products, which leave the oven during a self-cleaning operation. In actual practice, the burner flame is made large and the ow of such products passes through or over the flame so that certain constituents in the degradation products become incinerated before the products reach the exhaust vent 86. In any case, it will be apparent that the exhaust flowing out of exhaust vent 86 will be extremely hot. It will also be apparent that, if the hot exhaust was to directly contact the outer wall of the range or oven, the temperature of the wall would be raised considerably and, in fact, could be raised to a level which would present a fire hazard. This would be particularly true in cases where a kitchen wall or partition was located in close proximity to the range or oven. Since appliances of this type are often built in in modern kitchens, it becomes extremely important to provide means whereby the outer wall or walls of the appliances are kept at a low enough temperature to prevent this problem from arising. The combustion products passing out of the oven cavity 22 through vent 86 enter the vertical flue 88. Disposed within the flue 88 between the flue wall 92 and the rear insulation shield 38 is a ue box 96 having closed bottom and side walls 98 (FIG. 4) by which it is mounted on the rear insulation shield 38 of the oven over the exhaust vent 86. The back wall 94 of the flue box 96 is spaced between shield 38 and flue wall 92 to provide space for upward flow of cool air through ilue 88. It will be apparent from FIGS. 1 and 3 that, as the air passes upwardly through ue 88, it will pass upwardly behind the flue box 96, and in doing so will aid in cooling the flue box. Simultaneously therewith, air carrying the exhaust products from the oven will pass through opening 86 into the ilue box 96 and will exit from the upper end of the flue box. Above the ue box, the two separate streams of air and flue products will merge and will continue upwardly and eventually pass out of the structure through openings 90. Thus, the velocity of the combustion products leaving the liue box generate some inspiration of air which enters the lower portion of the oven and eventually passes outwardly through the exhaust vent 86 where it mixes with the thermally rising cool air in ilue 88.

It has been found that, when the exhausted products pass out through exhaust vent 86, the flue box will become heated in a concentrated area directly opposite the vent 86. Therefore, on the inner surface of wall 94 there is provided a deflector 100, shown most clearly in FIG. 4, which will cause the air flowing upwardly through 7 the ue box to become distributed throughout a wider area of the flue. This overcomes the problem of concentrated hot spots in the flue box.

It also has been found that still further improvement in the reduction of the amount of heat which reaches the outer wall of the appliance can be achieved by inserting one or more additional baffles or heat detlectors 102 as shown in FIG. 3. In a case Where baffles 102 are used, they will progressively reduce the temperature outwardly or in a direction away from the ue box.

It will be noted from FIGS. 1 and 3 that the outer Wall 92 of the flue 88 is solidly attached to the front wall 104 of the backsplash 16 immediately above openings 90 and functions to terminate the upper end of the Hue 88 and direct air out through vents 90.

ln accordance with a further aspect of this invention, additional improvements in cooling the outer surfaces or walls of the range or oven are achieved by providing a second ilue 106 which is disposed outwardly of inner flue 88. The outer Wall 108 of second flue 106 forms the extreme outer or back wall of the range which may be located in close proximity to a Wall or partition. The flue 106 communicates directly with the cool air supply beneath the range, and the stream of cool air owing upwardly through flue 106 passes over inner flue wall 92 and, consequently, reduces the temperature of wall 92. The llue 106 is exhausted through the backsplash 16 by means of additional vents 110 which are located above vents 90. If desired, a bale 112 may be inserted in ue 106 opposite exhaust vent 86 to divide the stream of air passing upwardly so as to more eiliciently cool this area of wall 92.

In some cases it may be desirable to provide additional means for cooling the oor beneath the oven or range and thereby prevent extreme amounts of heat from causing damage thereto. This can be achieved by providing a horizontal or transversely disposed panel 114 within the lower regions of the appliance between the floor and the lower shield or plate 63. The iow of cool air beneath panel 114 may be made to pass directly into the second ue 106 by connecting the panel 114 to wall 92, as shown in FIG. 1. Air is adapted to enter the regions of the appliance beneath the lower heating unit through a number of ports or openings 116, as shown in FIG. 2, and, if desired, inspiration of air may be urged by a fan (not shown).

It will be apparent that all of the objectives and advantages of this invention have been achieved by the provision of specially designed cooling llues 4which may be disposed outwardly of an oven opposite a wall which contains an exhaust vent, which wall may be any of the vertically extending walls of the oven. The baille 100 in flue box 96 will distribute the combustion products in such a manner that the mixture of combustion products and cooling air will leave the range at the top thereof distributed relatively uniformly over the width of the discharge area. The discharge ducts 90 and 110 may comprise openings in a grillwork across the backsplash or immediately thereabove, while the openings 116 at the bottom of the range may also constitute a portion of a grill, or, alternatively, a single relatively wide opening may be used. It is to be noted that, although the air movement in flue 88 is introduced partially by the effect of the velocity of the combustion products llowing from the flue box and partially by the thermal effect, air movement in llue 106 is induced thermally only.

It is to be understood that various modifications and changes in the structure shown and described can be made by those skilled in the art without departing from the spirit of the invention as expressed in the accompanying claims.

I claim:

1. An oven comprising a substantially box-like metal liner provided with top, side, bottom and back walls and having an open front, a door closing said front opening,

means for heating the interior of the liner,

an exhaust opening in one of said walls,

a lluebox having a closed bottom end and an open top end located opposite and communicating with said exhaust opening whereby exhaust products from within the oven are exhausted into the flue box,

means mounted externally of said liner and overlying said exhaust opening and llue box for guiding a stream of cooling air over the outer surface of said flue box and for mixing said cooling air with said exhaust products at a level above the flue box, and

dellecting means mounted in the flue box at a level higher than said exhaust opening for distributing the exhaust products over a relatively wide area.

2. An oven comprising a substantially box-like metal liner provided with top, side, bottom and back walls and having an open front, a door closing said front opening,

means for heating the interior of the liner,

an exhaust opening in one of said walls,

a flue box having a closed bottom end located opposite and communicating with said exhaust opening whereby exhaust products from Within the` oven are exhausted into the flue box,

a flue mounted externally of said liner and having a flue wall overlying said exhaust opening and flue box and spaced therefrom for guiding a stream of cooling air over the external surface of the flue box for cooling same, the upper end of the flue box open and communicating with the interior of the flue, the Hue having a terminating end wall at a level substantially above the ue box whereby said stream of cooling air merges with exhaust products passing out of the llue box at a level above the flue box,

said ue being provided opposite said exhaust opening with at least one vertically extending baille between and spaced from said ue wall and llue box for dividing said stream of cooling air into separate cooling streams, and

at least one exit vent in the flue adjacent said end wall for exit of the merged air and exhaust products.

3. An oven comprising a substantially box-like metal liner provided with top, side, bottom and back walls and having an open front, a door closing said front opening,

means for heating the interior of the liner,

an exhaust opening in one of said walls,

a flue box having a closed bottom end located opposite and communicating with said exhaust opening whereby exhaust products from Within the oven are exhausted into the iiue box,

a flue mounted externally of said liner and having a ue wall overlying said exhaust opening and flue box and spaced therefrom for guiding a stream of cooling air over the external surface of the flue box for cooling same, the upper end of the ilue box being open and communicating with the interior of the ilue, the ilue having a terminating end wall at a level substantially above the flue box whereby said stream of cooling air merges with exhaust products passing out of the llue box at a level above the flue box,

at least one exit vent in the flue adjacent said end Wall for exit of the merged air and exhaust products, and

a rear wall located substantially parallel `with and spaced from said flue wall to provide a duct external to said llue, said duct communicating with the atmosphere external to the oven to supply a stream of cooling air therefrom over said flue wall.

4. An oven as set forth in claim 3 wherein said duct contains at least one vertically extending bale opposite said exhaust opening between and spaced from said ilue wall and said rear wall for dividing the stream of cooling air llowing therethrough.

5. A household cooking apparatus including a cooking top, an oven beneath the cooking top, a rear wall rearwardly of the oven, and a backsplash above the back wall and cooking top, said oven comprising a substantially box-like metal liner provided with top, side, bottom and back walls and having an open front, a door closing said front opening,

means for heating the interior of the liner,

an exhaust opening in one of said walls,

a flue box having a closed bottom end and an open top end located opposite and communicating with said exhaust opening whereby exhaust products from within the oven are exhausted into the ue box,

a ue mounted between said liner and rear wall and overlying said exhaust opening and ilue box for guiding a stream of cooling air over the outer surface of said flue box and for mixing said cooling air with said exhaust products at a level above the ue box, and

deecting means mounted in the ue box at a level higher than said exhaust opening for distributing the exhaust products over a relatively wide area.

6. A household cooking apparatus as set forth in claim 5 wherein said Hue is provided opposite said exhaust opening with at least one vertically extending bafe between and spaced from said ilue wall and flue box for dividing the air flowing therethrough into separate cooling streams.

7. A household cooking apparatus as set forth in claim 5 wherein said flue has a flue wall spaced from said rear wall providing a duct therebetween external to said flue, said duct communicating with the atmosphere external to the oven for supplying a stream of cooling air therefrom over said flue Wall.

yS. A household cooking apparatus as set forth in claim 7 wherein said duct contains at least one vertically extending baie opposite said exhaust opening between and spaced from said ue wall and said rear wall for dividing the stream of cooling air flowing therethrough.

References Cited UNITED STATES PATENTS 2,158,881 5/1939 McCormick 126-21 X 2,743,719 5/1956 Reeves 126-21 3,150,655 9/1964 Saponara 126-21 20 IEDWARD G. FAVORS, Primary Examiner 

